The present invention relates to window shades and more particularly to multi-cellular window shades with retracting mechanisms that are hidden from view.
Multi cellular shades have become a desirable window treatment, particularly with modern construction that emphasizes large expanses of windows. The shades provide insulation for the windows while simultaneously providing a very attractive window covering that can be expanded and retracted as desired.
To maintain the overall appearance of the shade it is necessary to conceal the retracting mechanism from view. This is typically accomplished by enclosing the retracting mechanism in the multi cellular shade. Since the shade is multi-cellular, the retracting mechanism can be mounted in holes or slots formed along the outer edges of the shade without being visible.
Examples of concealed retracting mechanisms utilized in multi cellular shades are disclosed in U.S. Pat. No. 4,675,060 ('060) issued on Jun. 23, 1987 and in U.S. Pat. No. 4,647,488 ('488) issued on Mar. 3, 1987. As illustrated in the '060 patent, cords that form part of the retracting mechanism are threaded through holes that are drilled into the shade and into the header and footer of the shade assembly. Because of the cellular construction, the cords are hidden from view. Therefore, the shade can be expanded to its full length without the cords being visible. In addition, the '488 patent describes notching the cellular structure in the structure's center to locate a supporting member that allows the shade to be supported in non vertical applications by the contact of one side of the notch to the supporting member.
In PCT Application No. W090/06845 ('845), published on Jun. 28, 1990, an alternative design is shown which uses slots cut into the side edges of the shade for receipt of the retracting cord or other retracting means. As stated in the patent application, the design allows the inclusion of actuating and guiding means in the space between the structure's faces. This space can be pierced or slotted, or truncated in order to provide for any of the known actuating and guide means, without danger of binding.
Both of these shade designs for hiding the retracting mechanism have disadvantages. First, each has the potential for the shade to bind when it is being retracted or expanded. This can cause the shade to expand or retract unevenly, which is unsightly. It can also lead to wear of and possible damage to the shade. Still further, the retracting mechanism may be damaged. This is a particular problem when automated retracting mechanisms are used. In these applications, the shade must be supported in the window which is typically accomplished by the retracting means supporting the shade. Since the automated units rely upon some type of mechanical interaction between the driving means and the shade, binding of the shade could lead to misalignment of the mechanism and possible jamming of the retracting mechanism.
The above problems are more acute when the above designs are used in non vertical applications, such as for example in skylights. The shade disclosed in the '060 patent could have binding problems between the shade notch and the support member in non vertical applications. This is due to the requirement that the notch be no wider than the area between bond lines of the cellular structure. If the track is not exactly parallel to the notch, binding will occur.
In the '845 disclosure, the shade is supported by the track of the retracting mechanism as the shade is expanding and retracting. In these situations, the width of the slotting or notching of the shade and the thickness of the guidance means must be matched so that binding of the structure may be made to occur at some definable degree of expansion. However, this does require greater precision in manufacturing the shade due to the need for matching. Further, in these situations, there is the possibility that the shade will not be stiff enough at the areas contacting the shade, again resulting in an unsightly shade and possible damage to the shade.
The potential disadvantages were partially recognized in the '845 application. In the disclosure there is discussion about intended binding, although controlled, to aid in the expansion of the shade. (As should be appreciated by those of ordinary skill in this art, the amount of control can be difficult to achieve in many circumstances.) As further discussed in the application, "should certain installations (essentially horizontal) require maximum support within the shade, the truncated version of the slots 114 would most likely be used with the bonding line 112 structure used as the principal supporting surface contacting the guidance tongue 118." It further suggests that "additional coatings on the margins 115 may be applied during the adhesive strip application process. This would afford the notch 114 with a stiffened periphery and allow it to acquire the desired rigid character of the stiffened bond line 112." As should be appreciated, the additional gluing adds to manufacturing costs as well as the added cost to match the notch size to the track size.